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From: David Howells <dhowells@redhat.com>
To: Ian Kent <raven@themaw.net>
Cc: dhowells@redhat.com, Miklos Szeredi <miklos@szeredi.hu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	nicolas.dichtel@6wind.com,
	Christian Brauner <christian@brauner.io>,
	andres@anarazel.de, Jeff Layton <jlayton@redhat.com>,
	dray@redhat.com, Karel Zak <kzak@redhat.com>,
	keyrings@vger.kernel.org, Linux API <linux-api@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org,
	LSM <linux-security-module@vger.kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications [ver #5]
Date: Fri, 24 Jul 2020 12:36:03 +0100	[thread overview]
Message-ID: <2023286.1595590563@warthog.procyon.org.uk> (raw)
In-Reply-To: <865566fb800a014868a9a7e36a00a14430efb11e.camel@themaw.net>

Ian Kent <raven@themaw.net> wrote:

> I was wondering about id re-use.
> 
> Assuming that ids that are returned to the idr db are re-used
> what would the chance that a recently used id would end up
> being used?
> 
> Would that chance increase as ids are consumed and freed over
> time?

I've added something to deal with that in the fsinfo branch.  I've given each
mount object and superblock a supplementary 64-bit unique ID that's not likely
to repeat before we're no longer around to have to worry about it.

fsinfo() then allows you to retrieve them by path or by mount ID.

So, yes, mnt_id and s_dev are not unique and may be reused very quickly, but
I'm also providing uniquifiers that you can check.

David


  parent reply	other threads:[~2020-07-24 11:36 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-18 15:03 [PATCH 00/17] pipe: Keyrings, mount and superblock " David Howells
2020-03-18 15:03 ` [PATCH 01/17] uapi: General notification queue definitions " David Howells
2020-03-18 15:03 ` [PATCH 02/17] security: Add hooks to rule on setting a watch " David Howells
2020-03-18 18:56   ` James Morris
2020-03-18 15:03 ` [PATCH 03/17] security: Add a hook for the point of notification insertion " David Howells
2020-03-18 18:57   ` James Morris
2020-03-18 15:03 ` [PATCH 04/17] pipe: Add O_NOTIFICATION_PIPE " David Howells
2020-03-18 15:03 ` [PATCH 05/17] pipe: Add general notification queue support " David Howells
2020-03-18 15:04 ` [PATCH 06/17] watch_queue: Add a key/keyring notification facility " David Howells
2020-03-18 19:04   ` James Morris
2020-03-18 15:04 ` [PATCH 07/17] Add sample notification program " David Howells
2020-03-18 15:04 ` [PATCH 08/17] pipe: Allow buffers to be marked read-whole-or-error for notifications " David Howells
2020-03-18 15:04 ` [PATCH 09/17] pipe: Add notification lossage handling " David Howells
2020-03-18 15:04 ` [PATCH 10/17] selinux: Implement the watch_key security hook " David Howells
2020-03-18 19:06   ` James Morris
2020-03-18 15:04 ` [PATCH 11/17] smack: Implement the watch_key and post_notification hooks " David Howells
2020-03-18 15:05 ` [PATCH 12/17] watch_queue: Add security hooks to rule on setting mount and sb watches " David Howells
2020-03-18 19:07   ` James Morris
2020-03-18 15:05 ` [PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications " David Howells
2020-04-02 15:19   ` Miklos Szeredi
2020-06-14  3:07     ` Ian Kent
2020-06-15  8:44       ` Miklos Szeredi
2020-07-23 10:48   ` David Howells
2020-08-03  9:29     ` Miklos Szeredi
2020-08-04 11:38       ` Ian Kent
2020-08-04 13:19         ` Miklos Szeredi
2020-08-05  1:53           ` Ian Kent
2020-08-05  7:43             ` Miklos Szeredi
2020-08-05 11:36               ` Ian Kent
2020-08-05 11:56                 ` Miklos Szeredi
2020-07-24 10:19   ` David Howells
2020-07-24 10:44     ` Ian Kent
2020-07-24 11:36     ` David Howells [this message]
2020-08-03 10:02       ` Miklos Szeredi
2020-08-03 10:08       ` David Howells
2020-08-03 10:18       ` David Howells
2020-08-03 11:17         ` Miklos Szeredi
2020-08-03 11:49         ` David Howells
2020-08-03 12:01           ` Ian Kent
2020-08-03 12:31           ` David Howells
2020-08-03 14:30             ` Ian Kent
2020-03-18 15:05 ` [PATCH 14/17] watch_queue: sample: Display mount tree " David Howells
2020-03-18 15:05 ` [PATCH 15/17] watch_queue: Introduce a non-repeating system-unique superblock ID " David Howells
2020-03-18 15:05 ` [PATCH 16/17] watch_queue: Add superblock notifications " David Howells
2020-03-18 15:05 ` [PATCH 17/17] watch_queue: sample: Display " David Howells

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